Cadmium plating bath



Patented Oct. 24, 1950 Myron Diggin, Matawan,iand OttoiKaidosY, Leonardo, YN. J., 'assignors" to Hanson van winkle Munning Company, Ma t awan, J., a

l 'Seiial No.

;ur invention relates to alkali-cyanide ad- ;miumfpl'ating baths, andfgnoreparticularl to improvements in the compositionl a9??? 9 ance'of such baths. 'lmportant objects p'rovethe character'of the 'depos'itarrd' to" 'of in; i vestmen t m 1 v the plating range within which oth, cease deposits of bright or brilliant surface appearance are'obtained. v j f The objects of the invention are iobtainedby- }10 employing as addition agents'in the bath com; position one or more x e erqwe ie'FQW QPQ Icontaining an oxyheterocycl'ic"iing j of fisiii fi atoms; and hydroxyethyl cellu'lose, with or an outaddition of small quantities ofnickeli I which are soluble in the" cyanide loath" jThe S p'atent 0t Hogabo'orngsz Di ggin'. No 93L358,

patente d January .3, "1933, discloses" .tional alkali-cyanide cadmium plating "bath; 9 g which are added. as b right'enrs' arious... heterocyclic compounds. Such'b'ath's mayf b'e improved, in accordance with our inventionfb iv adding-about 0.025 120 0.2 gin/l. (preferably 0.1 gm'./l.), hydroxyethyl cellulose powder, or'equivalent amount of solution, and preferably also" small quantities of solublenickel salts.

.Conventional cadmium plating baths of .the alkali-cyanide type usually contain the following:

Cadmium metal' 2.0-4.5 oz. Y Total sodium cyanide Sodium hydroxide 1 Sodium carbonate Water to *make v arying amounts The following'eiiperimenfi were performed in Hull iCells' (250 ml.) on fjsheet steel cathodes ra-t .a total current of 1 ampere, 1.10 minutes plating time, room'temperature and with an aqueous bath made up as follows:

:. aza- Cadmium oxide 3'35 Sodium cyanide 14.5

Example 1.To 1 liter of the cadmium plating 1;

" "g. 1 Application can; "7,:

brilliance' ofthe deposit and extends thev current hfol'and 0.4 gram of nickel sulphate added to l liter of the cadmium plating lbath give 'only a *s'em'i bright electrodeposit from about am'psf/ I ftfupw'ar ds. The further addition of 10 001/1.

era 1% solution o'ffhydroxyethyl cellulose im- "proves' the semi-brightness to brilliance-from about-115mm amps/sq. it. and increases also I he brightness in the current density range below 1.15 amps/sq; ftf" r mp e 3. f The-addition'of grams furyl.

.acrylate and 052mm nickel sulphate to '1 "liter pi h? .bf i h 'depq s ove ,a' ge, c e (d ity ir a'i ifgei 'Ad ditiorijofflocop /l5 oi a*1%fsolutionof iurn' platingjbath gives milky, semiq hydroxyethylcelluloseimproves:th;semi brightto 'brill'anc at about 2,0 to amps/sq. "'ft. qsajrftple elq 'llie addition of loco/l. of a1 solutio'n"ofhydroxyethyl celluloseto a convefl;

tional cadmium platingbathwntaining 4 gm'sf/l. j

"h niat' nicke i h e r Eramp le 5 .'-The addition of 10 'ccj-of' a 1% solution of hydroxyethyl cellulose to 1' liter'ota cadmium plating bath containing 2 grams 'furoi'n fand 016 gram of nickel sulphate I increases the density-range 'for bright-deposits. 3

tion-lof hydroxyethyl-cellulose to a cadmium bath c'qnta'ining '1 gin/l. furyl nitroethylene improves noticeably the" brightness of the Hull Cell plate. j 'Exdm ZejZ-QThe addition of 10 cc./l. of a 1% so'lutiorrof hydroxyethyl cellulose to a cadmium platingbath containing 16 c./l. iurfurylamine and-0.6 gm'i/l; nickel sulphate improves "the bright quality of the plate and extends the curehtjdensity range *for' securing bright deposits. Example A cadmium plating bath. having dd'ed thereto '7z5 to -'1-1.25-'g'ms./l. *of caustic alkali -fuifiiral I 'rsm and 0.6 gm 1. nickel sulphate, gives semi-bright deposits from 15 amps/ sq. ft. upward. The .addition of 10 cc./l. of a 1% solution of hydroxyethyl cellulose gives a deposit of high brilliance.

Addition of hydroxyethyl cellulose to a cadmium bath containing only 7.5 to'11.5 gins/l. of caustic alkali-furfural resin but no nickel sul phate gives anoticeable increase in brightness. However, the best results are obtained from baths containingv all three addition agents.

Numerous plating tests have shown that the addition of 10 c. c./l of a 1% solution ofby droxyethyl cellulose, or 0.1 gm./1. of the solid sulphate "slig'htly ncreas s the brightness kali-furfural resin, with or without nickel saltsfi can be made to produce a noticeably brighter deposit by the addition of hydroxyethylcellulose.

The caustic .alkali-furfural pared, for example, by slowly adding .15 pounds of sodium hydroxide, dissolved in'30 pounds 'of.}" i.. water, to 67.5 pounds furfural while cooling and stirring, and then evaporating the reaction mix-4*;

ture to dryness under vacuum.

Example '9.. 'Brilliant-. deposits "are 7 obtained from cadmium' solutions containing smallqdan tities of. a high-boiling distillation residue,,.obitained as a by-product in the manufacture of tetrahydrofurfuryl alcohol, and furthermore hydroxyethyl cellulose and nickel salts. This dis,- tillation residue is a dark liquid, of moderate viscosity, a large 'part of which cannot be dis- --t illed 2,136 mm. pressure. It "contains consider,-

able amounts of oxyheterocycl'ic condensation 7 products, 1 as on treatment .Withphosphoric. acid considerable amounts. of tetrahydroiur'furyl .alf- ,cohol are obtained. .The,add ition o f. 3 grams of -this residue and 0.6 gram of nickel sulphate to 1 liter of:thefcadmium plating qbathg ive's allsmall Tbrigh t plating range atabout.BSiamps/sqJt. the..-Hull Ce1l,- and. the. furtherjadditionof l 0.; c. of hydroxyethyl cellulose l %,,fsolution)- widens the bright. platingcurrfent density- ;range considerably. i

scribe d,-are mixed with water to makeAOQ-c. c.

:of solution. The resulting very turbid solution -is treat ed with enough-activated carbon (Darco;

;-S5l) to give a clear filtrate; -The additionof 16 c. c. r of this clear 7 solution; corresponding ,to 54 grams of crude distillation residue, and-0.6 gram of nickel;sulphate. to' 1 liter of thecael- ,mium plating bath-gives a solution from which 'a semi-bright deposit is obtained at,about.-,l5 amps/sq. it, which increases in brightnessas the current density is-raiseduntil it becomes brilliant at about 40 amps/sq; ft. On the addition of 10 0. c. of" a 1%solution ofhydroxyethyl cellulose to this bath, a brilliant depositis ob- .tained fromabout 10 amps.-/sq.-ft. to about 40 amps/sq. ft. 1 I 1 qEazample r11.As reflect 'of adding -hydroxyethyl cellulose .to. an alkali-cyanide cadmium plating bath containing ,oxyheterocyclic addition. agents, we may refer A barrel plating cadmium solu,-

resin can be pref:

I -40. Example 10. ,l00 grams of the. distillation V a I further. 7 example 'ofthe to such baths in which the oxyheterocyclic compound is in the form of acids formed by Autoxi'dation of Furfural as described by Dunlop, Stout and Swadesh in Industrial and Engineer- 5 ing Chemistry, vol. 38, pages 705 to 708, July 1946, ,under the -name yof, Solid-Indicator acids.

On; addition of "2 i014. gms/l. of said acids f (brown powder) and of 0.6 gm./l. of nickel sulrphate to a cadmium plating bath, a bright cadrni 1 11n deposit is obtainable within a small range of rather high current density. The addition of 10 0.. c./l. of a v 1% solution of hydroxyethyl cellulose considerably increases the brightness .of the deposit andfalso considerably extends the ness occurs.

ltmay be mentioned that hydroxyethyl cellulose; seems to be quite stable in cyanide cadmium solutions; and that only relatively small replen ishments need to be made from time to time. yvemi Anfalka -cyanide cadi'niufm1 plating? c'ontair'iing v in,. ,soluti on as additionnagents ajn oxyhetero'cyclic compound selected "from ,the group .consisting. ,of furfury1 1alcohol, 'tetrahy :drofnrfuryl el c or, alkali, furyl acrylate, furoin, furyl nitroethylene, and; a bath-soluble caustic to 20 grnsl/ll, and said'cyanide cadmium bath alsogcontaining in solution 0.025,Itd0.2 "gm/l. hydroxyethyl cellulose. 2.', Ar 1 alkali-Qyanide cadmiuni plating bath containing in solution as addition agents .a bathsoluble nickel flsaltf in;. amounts' substantially equivalentgto d'oa c ,0j. 2 7}:grr 1./l. ofnnickel, and an oxyhe'terocyclic compound selectedfromto 2,01jgms./l.,, also: containing i dn'qxize E. CE C E Y The 0 llowing1.ref encsi are of, record 'inthe file Of this patent? UNITED STATES Number 1 Name I -,,Date

!Q W S OKU? l 2. 3 1,893,3684 :Hogaboom Jan.-3,';1933 zwv er e fe ..a

Feb: 8,-@-l938 FoREIGNrArEN rs ran'geiof currentdensity under which the bright-' 

1. AN ALKALI-CYANIDE CADMIUM PLATING BATH CONATINING IN SOLUTION AS ADDITION AGENTS ALL OXYHETEROCYCLIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF FURFURYL ALCOHOL, TETRAHYDROFURFURYL ALCOHOL, ALKALI FURYL ACRYLATE, FUROIN, FURYL NITROETHYLENE, AND A BATH-SOLUBLE CAUSTIC ALKALI-FURFURAL RESIN, IN AMOUNTS FROM ABOUT 1 TO 20 GMS./1/. AND SAID CYANIDE CADMIUM BATH ALSO CONATINING IN SOLUTION 0.025 TO 0.2 GM./1. HYDROXYETHYL CELLULOSE. 